Venketaraman- Antigen/Antibody rxns Flashcards
how many binding sites does a monomeric antibody contain and how many do pentamers contain?
2 and 10
when IgM’s come together and form a lattice by binding antigens, what is it called?
direct aggulatination
non IgM antibodies (like IgG) are monomers with two receptor sites do not form a lattice freely. what does it need to form a lattice? and what is the process called?
need to add secondary antibodies.
indirect (passive) aggulatination
if levels of anitbodies are greater than antigens, what precipitation zone are you in?
zone of antibody excess
how would you measure antigen concentration via single diffusion techniques? And what type of results do you get?
precipitation ring - quantitative
what technique requires serum proteins in a gel and in presence of electric current move according to size and charge? (followed by addition of antibodies)
immunoelectrophoresis - used to detect and quantify levels of serum proteins
what is radio-immunoassay and how does it work?
used to measure the amount of a substance in serum (hormones) by quantifying which radioactively labeled antibodies will bind to the substance (hormones).
How is ELISA used?
antigens or antibodies are covalently linked to an enzyme and addition of antibody or antigen will result in binding and substrate addition will result in enzyme-substrate reaction = color development = positive reaction/test result
what does the FACS (Fluorescent activated cell sorter) technique help to quantify in patients with HIV?
levels of CD4 cells, which indicates if HIV has progressed to AIDS (AIDS patients have a sharp decline in CD4 T cells)
a person with blood type B has which antigen on RBCs and produces what type of antibody?
B and Anti-A
What is the H antigen on RBCs?
N-acetyl glucosamine, fructose, and galactose on cell surface = H antigen
if a mother is Rh negative and has two successive children that are Rh positive, which fetus would be negatively affected?
the second one would die, because after exposure from the first fetus the mother made antibodies to Rh. (erythroblastosis fetalis)
if a drop of blood does not agglutinate with either A antibodies nor B antibodies, what blood group do you have?
O blood
How is ELISA used to detect HIV?
ELISA plate is pre-coated with HIV antigens, serum is added, antibodies bind to antigens in gel, secondary antibody or anti-antibody conjugated with enzyme horseradish peroxidase and substrate hydrogen peroxide are added - development of color = positive test result
how is a western blot used to confirm an HIV diagnosis?
antigens (gp 120 or gp 41) are run in gel electrophoresis, antigens are separated in gel based on molecular weight, antigens are transferred from gel to nitocellulose membrane. This is incubated with patients serum. Then you used to steps used in ELISA for presence of color bands.
In the direct type of Immunofluorescence, what 2 things can the antibody against the antigen covalently linked to
either fluorescent isothiocyanate (FITC) or phycoerythrin (PE). FITC = green and PE = red
In the indirect type of immunofluorescence, what binds to the primary antibody?
the secondary antibody is conjugated to FITC or PE and binds to primary antibody
what technique do the antibodies bind to bacterial or host antigen
immunofluorescence
How can you measure the proliferation of T cells
radioactive thymadine is added to cultures - which gets incorporated into DNA during cell division, cell division is measured after 18-24 hours
what is radioactive chromium labeling used for?
measure the cytotoxic activity of NK cells and cytotoxic T cells
what carbohydrates/sugars are added to the O blood group
no additional are added to H antigen
what carbohydrate/sugars are added to the A blood group
N-acetyl galactosamine is added to galactose
what carbohydrate/sugars are added to the B blood group
galactose is added to galactose
which blood group is the universal recipient
AB type
what is type 1 hypersensitivity reaction
fast (min-hrs) = allergic reaction
what is type 2 hypersensitivity reaction
complement activation reaction induced by antibodies binding to cell surface antigens (hrs-days) = hemolysis
what is type 3 hypersensitivity reaction
complement activation induced by soluble antigen-antibody complex that occurs in serum (hrs-days) = hemolysis
what is type 4 hypersensitivity reaction
delayed type hypersensitivity reaction (macrophages and T cells) (2-4 days)
how is a TB skin test performed?
myobacterial antigens are injected into forearm, antigen is presented by DC and macrophages to memory T cells, memory T cells proliferate and release cytokines (if induration occurs of more than 10mm - previously infected or + result)
